Steel Neck Bushing 0.243 Dia. by RCBS RELOADING PRODUCTSSteel neck bushing for RCBS Gold Medal Match dies. Works for the Gold Medal full length dies also. Proper neck bushing size can be determined two ways. Measure the outside neck diameter of your loaded cartridge; subtract 0.002" to 0.003". This allows approximately 0.001" of brass to spring back for correct neck tension. The other is to measure the neck wall thickness of your case and multiply by two and add the diameter of your bullet and subtract 0.001". RCBS suggests you have neck bushings one to two sizes about and below your target diameter.
